commit cb272843f2d5dfc4ef996ba952b99a3e30c88bbc
author Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Mon Dec 17 07:10:20 2018 -0800
committer GitHub <noreply@github.com> Mon Dec 17 07:10:20 2018 -0800
tree 01fea7a9e86083677614812e0b85b1c8a29732a1
parent c367d52a74781b2c9ffd9e29722fbdfc0234408c

bpo-35504: Fix segfaults and SystemErrors when deleting certain attrs. (GH-11175)

(cherry picked from commit 842acaab1376c5c84fd5966bb6070e289880e1ca)

Co-authored-by: Zackery Spytz <zspytz@gmail.com>

Modules/_io/textio.c

diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
index 9d0d9ca..49b545c 100644
--- a/Modules/_io/textio.c
+++ b/Modules/_io/textio.c
@@ -3049,6 +3049,10 @@
 {
     Py_ssize_t n;
     CHECK_ATTACHED_INT(self);
+    if (arg == NULL) {
+        PyErr_SetString(PyExc_AttributeError, "cannot delete attribute");
+        return -1;
+    }
     n = PyNumber_AsSsize_t(arg, PyExc_ValueError);
     if (n == -1 && PyErr_Occurred())
         return -1;